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UniStream advanced Modbus commands

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I've been told by UniTeam (Isreal) that a Unilogic release is coming soon with a (more) complete help section. 

You can always call tech support,  that's what I did on my first Unistream project. It was a SCADA system with 4 RTU's; MODBUS was pivotal. Dan Logee at UniT east coast was able to answer/resolve all my questions/issues.

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  • 8 months later...


I have the same question. Is there any detailed description somewhere yet?

My problem is Reading 2 values from a sensor. Using a Modbus simulator it Works fine from my PC, but not from the PLC.

The communication from my PC is shown in enclosed file.

When I use the "Modbus Read Builder" it seems that the "request buffer" is the same as TX in the enclosed document.

But I am not sure if (or how)  to use the "Read parser" to get the answer?

Thanks for an excelent software!


Anders Meeg






Modbus to DS80.docx

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Dear Meeg,

have you tried to take a look at the modbus advance examples (RS232, 485 and TCP); also, have you tried with the video tutorials?
I found these very helpful for me and now all my projects that include modbus work very well...both as slave, master or together.
how ever if you will post the part of the code where you are trying to use the parser (write and read), maybe, we will find the issue.

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Thanks for helping ORS!

I only had the the old example projects downloaded (from V1.15).

With the help from the Advanced commands in V1.19 I was able to see that the commands was OK.  It turned out to be a hardware problem. The sensor (ECD DS80 conductivity sensor) was not 100% rs485 compatible so I had to turn of the resistors on the CPU and use a 1k resistor instead.

By the way, do you know why it is 2 resistors on the CPU? And what size and how are the resistors connected?

The CPU manual does not give any details and normally only one 150ohm is used for cable termination. Is the two resistors for "pull up" and "pull Down" so that the line termination must be added externally?





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